Boat hull



1954 H. F. HlLLMAN ETAL ,160, 3

BOAT HULL 3 Sheets-Sheet 1 Filed March 21, 1962 INVENTORS. //nz.e Y EA614 MI/I q irraxwiyr 1964 H. F. HILLMAN ETAL 3,160,134

BOAT HULL INVENTORS. //4,e4 55 4 Lamaze-(x1,

5 Sheets-Sheet 3 M vm 1/ 3 BY 57, :454/6. Can/orig M Filed March 21.1962 United States Patent Ofiice ddfifiddd Patented Dec. 8, 19643,150,134 BSA! HULL Harry F. Hillrnan, Lake Forest, and Ralph E.Lambrecht and Warren C. Conover, Waukegan, llL, assignors to ()uthoardMarine Corporation, Waukegan, lit, a corporation of Delaware Filed Mar.21, 1962, fier. No. 182,719 29 Claims. (Cl. 114-665) The inventionrelates generally to boats incorporating planing hulls. Moreparticularly, the invention relates to three-point suspension hulls andto multiple-entry hulls.

A three-point suspension hull is defined as a planing hull including twoforwardly located planing surfaces or areas located at opposite sides ofthe fore and aft center line of the boat hull, and an after planingsurface or area extending along and symmetrically intersected by thelongitudinal center line of the boat hull. A multipie-entry hull isdefined as a unitary hull including more than one how formation whichcuts the water during movement of the hull. It is known to providethree-point suspension, multiple-entry, planing hulls of contours otherthan that claimed herein.

Three-point suspension permits carrying relatively larger loads Withrelatively smaller and particularly less wide after planing areas. Inaddition, the use of more than one planing surface serves to stabilizethe angle of attack during planing while the use of two forward planesprovides stability against rolling or side-to-side rocking of the hull.Angle of attack is defined as the angle measured in the direction ofmovement, between a planing surface and the theoretical surface level ofthe water. The multiple-entry feature aids steering by preventingbroaching, serves to facilitate beaching of the hull with the centerline thereof in generally perpendicular relation to the shoreline, andserves to minimize side-to-side tipping, both when the boat is beachedand when it is afloat.

The invention contemplates a hull providing the above features, as wellas other advantages. Specifically, the hull disclosed herein serves toavoid or eliminate cavitation and turbulence in the stream of wateracted upon by the propeller. As used herein, cavitation genericallyrefers :both to technical cavitation and to ventilation. Technicalcavitation is the formation of vapor pockets in the path of thepropeller in which the pressure is essentially equal to the vaporpressure of the surrounding water. Ventilation is defined as theformation of air pockets in the propeller stream due to entrapment ofair under the boat hull. Air may also be introduced into the Water inthe path of the propeller by turbulence, which is defined as a conditionof agitation produced, for example, by the entry of a bow formationthrough water. In general, undesirable air pockets are usually presentin turbulent water.

Reduction of turbulence and cavitation in the path of the propeller isachieved by the use of a triple-entry, three-point suspension hullincluding a bow incorporating (1) a center bow formation and a pair oflaterally spaced, forwardly located sponsons providing planing surfaces,and (2) means in the form of fins or spoilers which project downwardlyin parallel relation to the center line in the area between thesponsons' and the center bow formation. The spoilers are spacedoutwardly at opposite sides of the area into which the propeller orpropellers are advancing. Preferably, the spoilers are located inwardlyof the junction of the wakes from the center bow formation and therespective sponsons. The spoilers act as baffles or barriers tending toexclude turbulence created by the inside surfaces of the sponsons fromentering the otherwise quiescent water in the path of the propellers.This is of particular importance during acceleration or in a followingsea.

In the preferred embodiments, the spoilers extend rear- Wardly frompoints adjacent the bow and terminate adjacent the transom, therebyproviding barriers extending substantially the full length of the hullagainst the introduction into the path of the propeller of turbulentwater from the wake of the sponsons. When the spoilers extend to thetransom, they contribute materially to the lateral area which is wetted.The term wetted lateral area, as used herein, is defined as theprojected area of each part of. the hull below the water line in theprofile view plus the projected area of each keel and spoiler below thewaterline; that is, the projected area of each sponson is counted eventhrough the projections coincide and the projected area of each spoileris counted although they coincide and overlap with the hull projectionover part of their length. Wetted lateral area is important, in relationto the center of gravity, in obtaining superior turning action. In someembodiments, use of a downwardly projecting keel or center fin along theafter portion of the hull can be dispensed with.

If desired however, the spoilers may terminate substan tially forwardlyof the transom, but aft of the forward planing surfaces, and adownwardly projecting keel or center tin can be employed aft.

Turbulence in the path of the propeller is also avoided by constructingthe after plane with a positive dead rise angle, so as to effect lateraldisplacement of any turbu lence created by cutting-of the water by theforward point. of the after plane. The inclusion of a dead rise angle inthe after plane also aids in proper boat control and banking duringturns.

Dead rise angle is defined as the angle, measured in a station betweenthe base plane (or base line) and the laterally extending part of thestation (or station line) extending generally from the lowest point onthe station. Base plane is defined as the plane defined by the lowestpoint of each of the three planing surfaces. Station is defined as atransverse section perpendicular to the base plane and to the fore andaft center line of the hull.

The disclosed construction also advantageously facilitates planing ofthe boat hull at an optimum angle of attack with the center bowformation at least partially submerged in the water to assist inproviding in the path of the propeller a stream free of turbulence andcavitation. The optimum angle of attack represents that angle whereinthe sum of frictional resistance and wave-making resistance is at aminimum. Travel of the hull at its optimum angle of attack, whileretaining at least 'a part of the center bow formation in the water, isobtained by the provision of a knuckle or break in the angle ofincidence of the after plane.

Angle of incidence is defined as the angle, measured at any buttock,between the base plane and any partor extension of the buttock (orbuttock line) intersecting the base plane. Buttock is defined as a foreand aft section perpendicular to the base plane and parallel to the foreand aft center line.

As a result of the break or knuckle in the after plane, the planing areaforwardly of the knuckle has an angle of incidence less than the angleof incidence of that portion of the after plane rearwardly of theknuckle. In the disclosed construction, the forward portion of the afterplane extends parallel to the base line, thereby providing a generallytriangular planing area having a less sharply converging, forwardlyprojecting extension provided, at its foremost extremity, by a portionof the central bow formation.

Such an after plane formation additionally serves to increase thedistance between the propeller and the extreme forward end of the afterplane so as to further remove the 3 propeller from the area whereturbulence is created by passage of the central bow formation throughthe water.

In addition, the disclosed construction is designed to provide a softride, i.e., to reduce the pounding which commonly occurs incident tocrossing a series of two or more waves, and to aiford better steeringcontrol. More particularly, these advantages are obtained by reason ofthe use of a pair of relatively narrow sponsons having relatively largedead rise angles, which sponsons are symmetrically located with respectto the center line of the hull and are each generally symmetrical abouttheir individual center lines, at least in the area normally subject towetting during planing. This symmetry of design is specificallyadvantageous, coupled with the multiple-entry feature, in preventingbroaching.

The sponson construction is also designed to avoid suction loads duringmovement through the water. Such loads are undesirable as they tend toreduce speed and may tend to rock the boat if the sponsons are notsubject to substantially equal suction loads. This rocking effect isparticularly noticeable during turns and when crossing waves when thedepth of submergence of the sponsons may be different. Moreover, unequalsuction loading during a turn noticeably hinders return of the boat to astraight course.

Avoidance of suction loads is obtained by fabricating the sponsons withan absence of downward convexity and by the provision of buttocks havingportions which are straight throughout the area normally subject towetting during planing.

In addition to the before-mentioned advantages, including softer ride,better steering control and superior power utilization due to a minimumcondition of turbulence and cavitation in the path of the propeller, thedisclosed hull provides, as a result of its multiple-entry bow, anexceptionally large area available for use as a passenger cockpit,substantially increased forward buoyancy, and superior stability againstundesired tilting or tipping in any direction. Still further, the bowformation of the disclosed hull produces little wave generation orreflection during movement through the water, thereby also minimizingspray. It also serves to locate the center of gravity of the boat at arelatively more forward position than was heretofore generally the case.

Other objects and advantages of the invention will become apparent byreference to the following description and the accompanying drawings inwhich:

FIGURE 1 is a side elevational view of a boat hull embodying various ofthe features of the invention;

FIGURE 1a is a fragmentary side elevational view of a modifiedembodiment of boat hull incorporating various of the features of theinvention;

FIGURE 2 is a front elevational view of the boat hull shown in FIGURE 1;

FIGURE 2a is a fragmentary front elevation view, similar to FIGURE 2, ofthe modified boat hull shown in FIGURE 1a;

, FIGURE 3 is a rear elevational view of the boat hull shown in FIGURE1;

FIGURE 3a is a fragmentary rear elevational view, similar to FIGURE 3,of the modified boat hull shown in FIGURE 1a;

FIGURE 4 is a buttock or fore and aft sectional view taken generallyalong line 44 of FIGURE 2;

FIGURE 4a is a fragmentary buttock or fore and aft sectional view,similar to FIGURE 4, showing the corresponding buttock of the boat hullshown in FIGURE 1a;

FIGURE 5 is a fragmentary buttock or fore and aft sectional view takengenerally along line 5-5 of FIG- URE 2;

FIGURE 5a is a fragmentary buttock or fore and aft sectional view,similar to FIGURE 5, showing the corresponding buttock of the boat hullshown in FIGURE 1a;

FIGURE 6 is a fragmentary buttock or fore and aft l sectional view takengenerally along line 6-6 of FIG- URE 2;

FIGURE 7 is a fragmentary buttock or fore and aft sectional View takengenerally along line 77 of FIG- URE 2;

FIGURE 8 is a composite half station or transverse sectional view takengenerally along lines ll-l, 22, 3-3, 4- 4, 5-5, 6-6, and 7-7 of FIGURE1; and

FIGURE 9 is a composite half station or transverse sectional view takengenerally along lines 88, 99, and iii-4ft) of FIGURE 1.

The planing hull ill shown in FIGURE 1 of the drawings can be unitarilyconstructed of plastic and is symmetrical about its fore and aft centerline 13 (line 4-4; of FIGURE 2). The planing hull 11 includes amultipleentry bow 15 including a central bow formation 17 and a pair ofhow formations 1% respectively forming one part of each of a pair oflaterally spaced sponsons 2:1. The sponsons 21 provide forwardsupporting surfaces or planing areas 22 (see FIGURE 1), and togetherwith an after plane, indicated generally by the numeral 23, providestepped-three-point suspension. The sponsons 21 also serve to laterallyenlarge the bow is" and merge with the sides 25 which extend aft to atransom 27.

Extending aft from a point between each of the sponsons 21 and thecentral bow formation 19, in fore and aft parallel relation to thecenter line 13, is a spoiler 29. In the embodiment shown in FIGURE 1,the spoilers 29 terminate rearwardly of station 3- and prior to station9, as shown in FIGURES 8 and 9 and in FIGURE 5, and a fin 31, projectingdownwardly along the center line 13, is provided. However, in the boathull I'll, as shown in FIGURE 1a, which boat hull is generally ofidentical construction to the boat hull Iii except as will be noted, thespoilers 129 are extended to adjacent the transom I27 and the fin fillis omitted as sufficient wetted lateral area can be obtained by propervertical sizing of the spoilers 129. Extension of the spoilers toadjacent the transom 12.7 serves to provide a barrier, extending almostto the propeller area, against the entry of turbulence into the path ofthe propeller.

Considering the construction in greater detail, each of the sponsons 21is symmetrically located relative to the center line 13 and issymmetrical about its own center line b3, at least in the area normallysubject to wetting durlng planing. Each of the sponsons 21 is relativelynarrow and, as shown in FIGURE 8, includes, at each station, asubstantial dead rise angle, thereby providing a relatively soft rideand contributing to minimum wave reflection.

Each sponson 21 is also constructed, as seen best in FIGURE 8, so thateach station extends in a straight line from each side of its centerline 33 (stations 4 through 7), or is downwardly concavely facing oneach side of its center line 33 (stations 1, Z, and 3). Moreover, eachsponson 21 is also constructed so that the buttocks are straight, asseen in FIGURES 6 and 7, at least in the area normally subject towetting during planing. The provision of straight or downwardly concavestations together with straight buttocks avoids any downward convexityin the sponsons, and thereby eliminates suction loading thereof.

The after plane 23 extends forwardly from the transom 27 until mergingwith the central bow formation 17 and, as seen best in FIGURE 9, itincludes, at each station, a positive dead rise angle aifording lateraldisplacement of any turbulent condition created by passage of thecentral bow formation 17 through the Water. The construction of theafter plane is also free of any downward convexity. In addition, theafter plane 23 includes a knuckle or break 35, shown best in FIGURES 1and 4. The knuckle 35 generally divides the after plane into an aftportion 37 having substantially the same angle of attack as the sponsons21 and a forward portion 39 which has a zero angle of attack and whichincludes a progressively increasing dead rise angle, thereby effectingtransition of the after plane 23 into the central bow formation 17generally in the area of station 6. Breaking of the after plane, asindicated at 35, extends the rearward planing surface forwardly to atleast partially submerge the central bow formation 17.

The central bow formation is symmetrical about the,

center line 13 and, as seen best in FIGURE 2, is of less depth than thesponsons at all stations and merges into the after plane at or nearstation 6. As can be seen from FIGURE 8, each of stations 1 through 6 iseither straight or downwardly concave on each side of the center line13. Each station of the central bow formation 17 also includes apositive dead rise angle. If desired, the central bow formation can beomitted, while retaining certain of the advantages of the invention, asfor example, the soft ride, and the resistance to broaching.

Extending rearwardly into the after plane along the center line 13 ofthe hull from the central bow formation 17, is the central keel orfin.31. The fin 31 begins to appear at about station 6 and extendsalmost to the transom 27, providing suificient wetted lateral area toresist sidewise shifting or sliding during turns.

The spoilers 29 extend between the sponsons 21 and the central bowformation 17 from about station 2 to beyond station 8, i.e., Well beyondthe rearward end of the sponsons 21, and as seen best in FIGURE 8,provide a generally vertical surface or bafiie 41 against passage ofturbulence from the sponsons to the propeller path, while presentinginwardly and downwardly concave sides or surfaces 43 toward the centralbow formation 17, thereby tending to deflect curvilinearly downwardlyany turbulence created by passage of the central bow formation 17through the water, and thereby permitting passage of such turbulencepast the spoilers 29 and out of the propeller path.

As can be seen from the drawings, the side and trailing edges of theplaning surfaces terminate abruptly along sharp lines, therebypreventing water from following. In particular, at the rear of eachsponson 21, there is provided a vertical step in order to mark abruptlythe end of the sponsons. Preferably, the step is only of such height aswill prevent following of the water, and there extends, from the topmargin of the step, an arched portion of the hull which extendsrearwardly and merges into the after plane. The arched portion,indicated at 45, provides improved structural strength over that whichwould result if the rear surface of the sponson were completely orsubstantially planar.

Various of the features of the invention are set forth in the followingclaims.

What is claimed is:

1. In an integral multiple-entry planing hull including a bow having asponson spaced laterally on each side of the center line of said hulland an after plane extending aft of said sponsons, the improvementcomprising sponsons which are symmetrical with respect to said centerline and which are individually symmetrical at every station at leastWithin the area normally subject to wetting during planing.

2. A boat hull in accordance with claim 1 wherein each of the sponsonstations incorporates a positive dead rise angle, and is free ofconvexity within the area normally subject to wetting during planing.

3. A boat hull in accordance with claim 1 wherein each sponson buttockis straight within the area normally subject to wetting during planing.

4. A boat hull in accordance with claim 1 wherein each sponson stationincorporates a positive dead rise angle and is free of convexity withinthe area normally subject to wetting during planing, and each sponsonbuttock is straight within the area normally subject to wetting duringplaning.

5. In a three-point suspension planing hull including an after plane andtwo laterally spaced forward planes disposed at acute angles to the baseline, the improvement comprising means providing a break in said afterplane midway of its fore and aft length with the portion of said afterplane forwardly of said break being disposed at a lesser acute angle tothe base line than the portion of said after plane re arwardly of saidbreak.

6. A boat hull in accordance with claim 5 wherein said forward portionof said after plane has a zero angle of incidence.

7. A boat hull in accordance with claim 5 wherein each station throughsaid after plane includes a positive dead rise angle.

8. A boat hull in accordance with claim 5 wherein each station throughsaid after plane is free of downward convexity in the area normallysubject to wetting during planing and each station through said afterplane includes a positive dead rise angle.

9. In an integral multiple-entry planing hull including a center bowformation merging into an after plane and a laterally spaced sponson oneach side of said bow formation providing a pair of laterally spacedforward planes, with said planes being disposed at acute angles to thebase line, the improvement wherein said sponsons are symmetrical withrespect to said bow formation and are individually symmetrical at everystation at least within the area normally subject to wetting duringplaning, and

said after plane incorporates a break therein midway of its fore and aftlength, thereby defining a forward portion and an after portion, saidforward portion of said after plane being disposed at a lesser acuteangle to the base line than the rearward portion of said after plane.

10. A boat hull in accordance with claim 9 including a downwardlyprojecting spoiler extending parallel to the center line of the hullbetween each of said sponsons and said center bow formation.

11. A boat hull in accordance with claim 10 wherein said hull includes atransom, and said spoilers extend through said after plane substantiallyto said transsom.

12. A boat hull in accordance with claim 10 wherein said spoilers eachinclude a portion having a concave surface on the side thereof adjacentto said center bow formation and a generally vertical surface on theside thereof facing outwardly of the center line.

13. A boat hull in accordance with claim 9 wherein each station throughsaid after plane includes a positive dead rise angle and is free ofdownward convexity in the area normally wet during planing.

14. An integral, multiple entry planing hull including a bow having asponson spaced laterally on each side of the center line of said hull,said sponsons each being symmetrical with respeot to said center lineand each being individually symmetrical at every station at least withinthe area normally subject to wetting during planing, an after planeextending aft of said sponsons, a transom, and a downwardly projectingspoiler extending pmallel to said center line between each of saidsponsons and said center line and extending along said after planesubstantially to said transom.

15. An integral, multiple entry planing hull including a transom, a bowhaving a sponson spaced laterally on each side of the center line ofsaid hull, said sponsons each being symmetrical with respect to saidcenter line, each being individually symmetrical at every station Withinthe area normally subject to wetting during planing, and eachterminating substantially forwardly of said transom, an after planeextending aft of said sponsons, a downwardly projecting spoilerextending panallel to said center line between each of said sponsons andsaid center line, said spoilers terminating substantially forwardly ofsaid after plane and rearwardly of said sponsons, and a fin projectingdownwardly from said after plane along said center line to a point nearsaid transom.

16. An integral, multiple entry planing hull including a bow having asponson spaced laterally on each side of the center line of said hull,said sponsons each being symmetrical with respect to said center lineand each being individually symmetrical at every station at least Withinthe area normally subject to wetting during planing, and a downwardlyprojecting spoiler extending parallel to said center line between eachof said sponsons and said center line, each of said spoilers including aportion having a generally Vertical surface facing outwardly from thecenter line of said hull.

17. An integrfl, multiple entry planing hull including a bow having asponson spaced laterally on each side of the center line of said hull,said sponsons each being symmetrical with respect to said center lineand each being individually symmetrical at every station at least withinthe area normally subject to wetting during planing, a downwardlyprojecting spoiler extending parallel to said center line between eachof said sponsons and said center line, each of said spoilers including aportion having a generally vertical surface facing outwardly from thecenter line of said hull, and an inwardly facing concave surface on theside thereof adjacent to said center line.

18. An integral, multiple entry planing hull including a transom, a bowhaving a sponson spaced laterally on opposite sides of the center lineof said hull, said sponsons each terminating forwardly of said transom,each providing a planing surface, each being symmetrical with respect tosaid center line, each being symmetrical with respect to its own centerline within the area normally subject to wetting during planing, eachincluding a positive dead rise angle within the area normally subject towetting during planing, each being free of downward convexity within thearea normally subject to Wetting during planing, and, at each buttock,each being straight within the area normally subject to Wetting duringplaning. 7

V 19. An integral, multiple entry planing hull including a transom, abow having 'a sponson spaced laterally on opposite sides of the centerline of said hull, said sponsons each being symmetrical with respect tosaid center line,

each being individually symmetrical at every station at least within thearea normally subject to wetting during planing, and each terminatingforwardly of said transom.

20. An integral, multiple entry planing hull including a transom, a bowhaving a sponson spaced laterally on each side of the center line ofsaid hull, said sponsons being symmetrical with respect to said centerline, being individually symmetrical at every station within the areanormally subject to wetting during planing, and terminating forwardly ofsaid transom, and an after plane extending along said center linebetween said sponsons and said transom.

References Cited in the tile of this patent UNITED STATES PATENTS

1. IN AN INTEGRAL MULTIPLE-ENTRY PLANING HULL INCLUDING A BOW HAVING ASPONSON SPACED LATERALLY ON EACH SIDE OF THE CENTER LINE OF SAID HULLAND AN AFTER PLANE EXTENDING AFT OF SAID SPONSONS, THE IMPROVEMENTCOMPRISING SPONSONS WHICH ARE SYMETRICAL WITH RESPECT TO SAID CENTERLINE AND WHICH ARE INDIVIDUALLY SYMMETRICAL AT EVERY STATION AT LEASTWITHIN THE AREA NORMALLY SUBJECT TO WETTING DURING PLANNING.